Support for more database types (Postgres, MariaDB) + auto-reconnect

• Adds official support for new database types (postgres, mariadb) (@Xavierhorwood #520)
• Database configuration is now set through db_type, db_host, db_db, db_user, and db_pass (@Xavierhorwood #520) Previous mysql_* settings still work this version, but are set for deprecation (See more info below)
• Adds auto_reconnect settings, to enable auto-reconnect on database connections (@Xavierhorwood #520)

⚠️ DEPRECATION WARNING ⚠️
If you are currently using a MySQL database on your existing BedrockConnect setup, your current configuration may not work in future versions. Read more here: https://github.com/Pugmatt/BedrockConnect/wiki/Deprecated-Database-Settings